Since the early 90's the use of infusion pumps to administer anesthetics has become common practice for achieving continuous regional and local anesthesia. These pumps are either electro-mechanical pumps or mechanical pumps. Most pumps are designed to be ambulatory, carried by the patient in a pouch or similar holder. Some types of pump are suitable for Patient Control Analgesia (PCA) whereby the patient can add additional medication bolus to the basal flow to address severe pain.
Currently there are two main clinical procedures that are used for continuous long-term postoperative regional/local anesthesia, both are subcutaneous/intramuscular. The first procedure is Surgical Site Infiltration (SSI), wherein the medication is introduced into or nearby the surgical incision by use of a catheter with a long fenestrated segment inserted into the patient tissue. The second procedure is Continuous Peripheral Nerve Block (CPNB), wherein medication is introduced proximate to the nerve that controls the limb that has been operated. When CPNB administration is performed, an efficient pain block is achieved due to medication saturation of an area surrounding the nerve. Therefore maintaining sufficient nerve bathing is essential to gain continuous pain blockage. For example, such sufficient nerve bathing is achieved when a nerve block is performed by manual injection, typically performed prior to surgery. One of the main objectives of the present innovation is to continuously maintain sufficient nerve bathing through implementing an innovative infusion strategy for CPNB and thereby gain an improved post-operative pain therapy.
Automatic pumps for continuous medication insertion are well known in the art, for example, insulin pumps. Such devices are configured to continuously inject small amounts of medication, for example, in the order of 1 ml/hour (0.017 milliliter/minute), intravenously (IV) into a human venous. The amounts of medication injected intravenously must be closely controlled as not to harm the venous while continuously injecting the medication. Other IV pumps known in the art can inject larger amount of medication even up to 30 ml/min, however such pumps are not designed to endure pressures higher than 0.5 bar. Such pumps do not suit to infuse regional/local anesthesia as required to simulate manual injections; rapid infusion of relatively large amount of anesthetic medication at a relative rapid velocity that is administrated through relative thin and long catheter; requires relatively high pressure, for example, volume of more than 2 ml in a velocity of at least 5 ml/min with 20G catheter 50 to 100 cm long required a pressure of at least 2.0 bar.